The life stories being told in Professor Marston and the Wonder Women are truly radical. William Marston (Luke Evans) was a psychologist and university professor who helped invent the lie detector in the 1920s and created the character of Wonder Woman for DC Comics in 1941. His wife Elizabeth (Rebecca Hall) was a brilliant psychologist in her own right; together, they had a long and unconventional romantic partnership with their research assistant Olive Byrne (Bella Heathcote), who was credited as the visual inspiration for Wonder Woman (among other things, she sported a pair of gold bracelets).

The strange arc of Marston’s career is fascinating, and the unusual nature of his relationship with Elizabeth and Olive even more so. Professor Marston and the Wonder Women suffers whenever it tries to tell that story in an ordinary way, boiling the details of Marston’s life down into a typical biopic format that makes sure to check off all of his eclectic achievements. Still, the romance being explored here—which so rarely gets the Hollywood treatment, and which the writer/director Angela Robinson takes such care to flesh out—is enough to keep things from ever feeling too staid.

Robinson was an exciting talent of the Aughts who hasn’t made a film in 12 years (she’s worked in TV since making the lesbian action-comedy D.E.B.S. in 2004 and the Disney feature Herbie Fully Loaded in 2005). It’s exciting to have her perspective back on film, especially because Professor Marston and the Wonder Women immediately makes it clear just how uninterested it is in the “very special man” framing so many biopics adopt. Evans is charming in his careful, slightly manicured way as Marston, but Robinson is immediately much more interested in the two women in his life, and the fascinating ways their relationships intersect with both him and each other.

The real star of Professor Marston and the Wonder Women is Rebecca Hall, who’s an absolute dynamo as Elizabeth Holloway Marston, a frustrated academic doing research alongside him and chafing at the fact that he’s getting his Ph.D. at Harvard while she has been ghettoized at its sister school, Radcliffe. Elizabeth is neurotic, sometimes brutally blunt, and overtly frustrated at the lack of opportunity available to her in the ’20s. She loves Marston for his intelligence and his radical notions of interpersonal relationships, but has no illusions about his flaws, nor her own; when she meets Olive for the first time, she loudly orders her to never sleep with her husband, which sends Olive out of the room crying.

The specifics of William, Elizabeth, and Olive’s relationship are somewhat murky because they kept their polygamous arrangement secret at the time, but Robinson wants to celebrate their atypical love story rather than pick it apart. It’s genuinely daring how Robinson depicts the evolution of their love, from Olive’s girlish fascination with William to her deeper infatuation with Elizabeth; this is a film that doesn’t fetishize their fluid sexuality and make it a sideshow to be gawked at. It’s the underpinning of everything that drives Marston, from his invention of the lie detector (which monitored a subject’s blood pressure to gauge emotional responses to probing questions) to the genesis of Wonder Woman.

It’s a shame that, while the relationship is invested with rich energy, the rest of the film, particularly the comic-book material, feels a little rote. Marston’s storytelling in the pages of Wonder Woman—including the comic’s imagery of bondage and homosexuality—was so shocking at the time that it provoked cries of alarm from the Child Study Association, whose director Josette Frank is played by Connie Britton as a hectoring scold. Her scenes serve as a dull framing device for the film, carrying us through Marston’s career and helping connect dots that the audience should be able to figure out for itself.

For instance: Wonder Woman has a lasso of truth, not unlike Marston’s famous lie detector (which had to be wrapped around a person’s torso). And yes, Marston had publicly expressed interest in bondage and dominant/submissive relationship dynamics, which he poured into his comic-book character in hopes of educating the nation’s youth and advancing radical feminism. But Robinson drives each of these points home too hard by intercutting the Josette Frank scenes and having her point out all of these links between his art and his life; Marston’s fascination with depicting feminine strength in his comics, then seen as highly unusual, is also reduced to a few quick, punchy montages.

No matter. Professor Marston and the Wonder Women might succumb to plenty of biopic clichés—its score sounds like a bouncy temp track, and one character’s impending lethal illness is suggested by an ominous cough into a handkerchief. But beyond these little narrative shortcuts, the attention paid to Elizabeth and Olive’s roles in every aspect of Marston’s crazy life is enough to brighten this film.

Robinson is building to a visual reveal—the sight of Olive, wearing her bracelets and holding a lasso given to her by Elizabeth, which supposedly inspired Marston to create his female superhero. But rather than serving as a cheap reference to his most famous creation, the moment rings true as an emotional expression of his love for these two women. That authenticity is what carries Professor Marston and the Wonder Women and makes it worth watching.

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David Sims is a staff writer at The Atlantic, where he covers culture.